This invention relates generally to electrical signal preamplifiers, and more particularly the invention relates to a preamplifier for magneto-resistive heads as used in reading data from magnetic tapes.
Recent developments in high density read-channel head technology have resulted in magneto-resistive (MR) heads which need bias currents up to 20 mA while delivering up to 20 mV of signal amplitude. Even so, very low noise levels are still necessary to pick up much smaller signals while also being capable of handling relatively large signal swings at high frequencies. Miniaturization of tape and disk storage technology requires the integration of more than one preamplifier along with biasing capabilities for both read and bias MR heads.